Rate Control For Streaming Media Transmission Over Wireless Mesh Network

In recent years, the developments of wireless accessing techniques, especially those of Wireless Mesh Network (WMN), have paved the way to popularize wireless streaming media services. WMN owns some advantages, such as high reliability and good scalability. However, it also brings new challenges and pressures in rate contol scheme due to the features of WMN communication environment and streaming applications in the following issues: One of the key problems for rate control streaming over WMN is how to adapt to features of links including high transmission Bit Error Rate (BER) and timely variation. Another is to provide capability to resist interference among the nodes. In addition, it should improve TCP fairness and throughput performance when transmitting streaming over WMN.To solve the above problems, this thesis addresses on rate control for streaming media transmission over WMN. The content of this thesis includes four issues: (1) researching on rate control in link layer to satisfy streaming media transmission; (2) researching and modeling on rate control to minimize transmission delay for streaming media; (3) rate control equation TCP-friendly streaming media access based on packet differentiation; (4) modeling on multipath rate control for streaming media based on Multiple Descriptions Coding (MDC).The work in this thesis has been supported by the National Science Foundation of China"Investigation of Wireless Multimedia Techniques based on Multimedia Transmission Property"(No.60202005) and the National Science Foundation of China"Research on Interactive streaming delivery based on Internet"(No. 60302004), and also supported by the National Science Foundation of Hubei province"Research on network cache for streaming based on quality-time 2D attributes"(No. 2005ABA264). The contributions of this thesis include:(1) Research on link layer rate control base on interference range constraint: This thesis proposes a model to describe the relation between interference range and transmission rate. Based on this model, a rate control algorithm to resist interference from distance nodes based on adjusting interference level is presented with a cross layer policy to guarantee FER, which build a tradeoff between FER and transmission rate and provide best effort PER-guaranteeing service for streaming transport. Simulation results demonstrate that lower PLR, smoother sending rate and better performance can be achieved by our proposed mechanism when transmitting streaming in WMN.(2) Variable-Packet-size Rate control based on transmission delay minimum: In order to getting rid of the shortages of ARQ in link layer, this thesis proposes a delay-constrain theory based rate control scheme for streaming media transmission in WMN by researching on the policy of transport layer packet size adjustment according to delay-constrain equation by considering wireless Packet Retransmission Rate (PPR). The theoretical model and relevant detailed deduction are also presented. Simulation results demonstrate our proposed mechanism can effectively improve transmission delay and jitter performance of streaming media transmission over WMN.(3) TCP-friendly Rate control scheme base on ratio of loss differentiation: Considering statistic features of packet loss due to error and congestion events in WMN,this thesis proposes a TCP-friendly rate control equation for streaming media delivery based on ratio of loss differentiation. Besides, a practical rate control mechanism is constructed. Simulation results demonstrate that higher throughput, better fairness and smoother sending rate can be achieved by our proposed mechanism.(4) Research on cooperative rate control for MDC transmission over WMN: Considering feature of path diversity in WMN, this thesis proposes a MD rate allocation algorithm based on MDC adopting H.264 technique to satisfy MDC transmission delay constrains and prevent buffer overflow. Simulation results demonstrate that this mechanism can depress PLR and improve QoS performance of MDC transmission with MPT.